Throughout the disclosure, various technical and patent literature are identified by a bibliographic citation. The contents of all technical and patent literature are incorporated into the present disclosure by reference in their entirety.
Film forming materials have broad use in therapeutic, cosmetic and personal care applications. Such materials are used to coat a body surface, such as skin, nail and hair, for the protection of the surface or to apply therapeutic or cosmetic ingredients to the surface.
The film forming process typically involves a chemical reaction and solvent evaporation. The chemical reaction, such as polymerization of cyanoacrylate, can be quickly initiated by water or keratinous protein and forms a polymeric film on a surface. Alternatively, the chemical reaction may be epoxy-curing, UV or thermal polymerization of unsaturated monomers, radiation-induced curing or other ring-opening reactions.
Solvent evaporation, on the other hand, can help form a uniform layer of film on the surface. Water is widely used as a non-toxic solvent or as a dispersing medium as in the cases for latex and dispersions. Alcoholic solvents are another group of solvents, although many film forming materials have limited or no solubility in these solvents. Other examples of organic solvents include alkyl acetate, acetone and toluene.
Many film forming materials rely solely on the physical interactions between the material and the body surface to adhere to the surface. These interactions include van de Waals forces, dipolar interaction and hydrogen bonding. In general, these interactions are relatively weak, which often leads to poor adhesion to the skin and premature flake-off of the resultant film. Moreover, grease and sweat on the skin, for example, can further weaken the adhesion.
There has been a long felt need for improved film forming compositions, which are simple to apply, can form a flexible film quickly and adhere strongly to a substrate. It is also preferred that the formed films are breathable and non-toxic.